This invention relates to a storage bag for bulk, dry, powdered product, such as a powdered milk product. More particularly, it relates to a bag in this category which is specially prepared for the concealed-value exo-venting of bag-trapped gas and moisture that ends up residing inside the bag following product filling and sealing.
It is typical for such a bag to be constructed, as an illustration, from plural thin layers of material, including paper material, as well as at least one layer which is formed of a moisture- and gas-impervious plastic material (layer). The present invention proposes the incorporation, at a special location and region concealed within such a bag, of a uniquely organized and arranged valving structure which allows for the reliable exo-venting (one way only) of otherwise trapped moisture and gas.
With regard to a bagged bulk product such as dry milk, bag-retained excess moisture and gas can cause problems. Retained moisture can cause product degradation, and excess retained gas can create a bag ballooning effect which leads to bag-stack unstability in palletized loads of plural, stacked bags. It is thus very important to provide a mechanism for permitting the unidirectional, outward venting of as much otherwise retained moisture and gas as possible.
Preferably, the venting of a bag to allow for the escape of such trapped moisture and gas is accomplished in such a manner that venting capability will not be compromised (blocked) by the very act, and indeed the normally expected act, of stacking bags in a close side-by-side relationship and one on top of another. In other words, bag venting structure preferably must not be so located in a bag that overlying stacked bags which mutually sit upon one another, and next-adjacent side-by-side bags, can cause occluding of that important structure. Additionally, it is desirable that any one-way valve which is employed for exo-venting purposes be concealed by a region of a bag layer from the outside so that its reliable functionality is not unnecessarily compromised by exposure-related damage.
The present invention addresses these issues in a very practical and satisfactory manner, and in plural proposed embodiments, in each of which, an exo-valving structure is uniquely incorporated into the bag in a concealed manner to permit outward passage of gas and moisture through the moisture and vapor barrier layer in the bag, and at a location which essentially will not become blocked under ordinary and conventional bag-stacking and handling operations and conditions. The various important features and operating advantages of the present invention will become fully apparent as the description which now follows is read in conjunction with the accompanying drawings.